CHRIS CAGLE GETS THE BIRD -- FROM A FAN!

Seems that fans in Marquette, Iowa are serious about their concerts -- one fan gave Chris Cagle the finger because fans rushed the stage and she couldn't see the show.

The woman, who also reportedly mouthed an insult, riled Cagle up enough to stop the show and ask her why.

"After the song was over, I said, 'Where's that lady that just shot me the bird and told me to f*** off?'" said Cagle in an interview. "What did I do to you to make you pay just so you could flip me off?"

Once she explained, she was offered a new seat right next to the stage -- so close to the action that, "I literally dropped sweat on her," said Chris.